This is kind of... Well, good news, I suppose? It depends on where you allegiances lie, but it seems like Ubuntu is warming up to the idea of using Qt to develop applications. It's no secret that Qt is a far more advanced development framework than Gtk+, so it only makes sense for Ubuntu - a GNOME/Gtk+ distribution - is looking at it.

...but rather *why* should I learn about Qt? What would it get me? Why is it better than the technologies that the Gnome world uses?

If you're looking at it from that point of view then you're going to find yourself in troll territory pretty quickly one way or the other.

Do you enjoy copying and pasting code from libegg, libsexy or anything else directly into your applications as you try and solve dependency hell? Hint, no one feels the need to do that with Qt. Would you like cross-platform applications to work? Do you enjoy using half a dozen different libraries in your applications besides GTK that all look and program differently? Do you really think that has ever been a good idea?

You can find a lot of things saying "Qt is superior" without any real details about what makes it superior.

If you can't glean some of the avantages from the above list then there's little that can be done for you.

Like I said, I know quite a bit about GTK development -- I do it for a living...

What kind of applications do you work on would be a good place to start. Anyone I have known who has ever done .Net, Cocoa, Qt or even MFC programming and has looked at GTK+ have said "If that's Linux development then no wonder it has no applications. I'm not going to write them".

You've probably been doing GTK programming for two long. Ask some Windows and Mac developers what they think because they're who the Linux desktop needs to grab.